Image projection device and projection device

ABSTRACT

The present invention is an image projection device that includes: a light source 12 that emits a laser beam 34; a scanning mirror 14 that two-dimensionally scans the laser beam 34 emitted from the light source 12; and a projection mirror 24 that projects scanned light onto a retina 26 of an eyeball 22 of a user to project an image onto the retina 26, the scanned light being composed of the laser beam 34 that has been scanned by the scanning mirror 14, wherein the laser beam 34 emitted from the light source 12 is scanned by using a part of an operating range of the scanning mirror 14.

TECHNICAL FIELD

The present invention relates to an image projection device and aprojection device, and more particularly relates to, for example, animage projection device that projects an image onto the retina of a userand, for example, a projection device that projects a laser beam ontothe eyeball of a user.

BACKGROUND ART

There has been known an image projection device that projects a laserbeam onto the retina of a user while scanning the laser beam to allowthe user to recognize the residual image of the scanned laser beam overthe retina as an image. Such an image projection device is stronglyrequired to be smaller. Thus, there has been suggested an imageprojection device that uses, for example, a laser diode to reduce thesize and electrical power consumption thereof. Additionally, there hasbeen suggested an image projection device that uses a low-power laserdiode for the safety of the eyes of the user (e.g., Patent Document 1).

PATENT DOCUMENT

Patent Document 1: Japanese Patent Application Publication No. 11-64782

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

Since the eyeball of the user moves, the scanned laser beam may becomenot projected onto the retina, and thereby the user may not recognize animage. Even when all of the scanned laser beam is projected onto theretina and the user can recognize the entire image, the user mayrecognize a distorted image. Furthermore, the beam spot size of thelaser beam projected onto the retina increases, and thereby a somewhatdefocused image may be obtained.

When a projection mirror is located on the eyeball side surface of thelens of glasses and is used to project the laser beam onto the eyeballof the user, it may be difficult to achieve both the function as aprojection mirror and the function as a lens of glasses.

The present invention has been made in the view of the above problems,and aims to provide an image projection device capable of providing agood image to the user, or a projection device capable of achieving boththe function as a projection mirror and the function as a lens ofglasses.

Means for Solving the Problem

The present invention is an image projection device characterized byincluding: a light source that emits a laser beam; a scanning unit thattwo-dimensionally scans the laser beam emitted from the light source;and a projection mirror that projects scanned light onto a retina of aneyeball of a user to project an image onto the retina, the scanned lightbeing composed of the laser beam that has been scanned by the scanningunit, wherein the laser beam emitted from the light source is scanned byusing a part of an operating range of the scanning unit. The presentinvention can provide a good image to a user.

In the aforementioned configuration, the laser beam emitted from thelight source may be scanned in different positions within the operatingrange of the scanning unit in accordance with a move of the eyeball ofthe user.

In the aforementioned configuration, a controller that generatescorrected image data by gradually changing height of an image of inputimage data from a first vertical side to a second vertical side andgradually changing curvature of the image from the first vertical sideto the second vertical side may be provided, and the laser beam may beemitted from the light source based on the corrected image data.

In the aforementioned configuration, a controller that generatescorrected image data by rotating an image of input image data andgradually changing curvature of the image from a first vertical side toa second vertical side may be provided, the scanning unit of which ascanning amplitude in a horizontal direction gradually changes in avertical direction may be rotated to be used, and the laser beam may beemitted from the light source based on the corrected image data.

In the aforementioned configuration, the scanned light may be convergedat a side of the retina beyond a pupil of the eyeball of the user by theprojection mirror.

In the aforementioned configuration, the projection mirror may have afree curved surface, or have a compositional structure of a free curvedsurface and a diffraction surface.

In the aforementioned configuration, an optical means that allows alaser beam in the scanned light to enter the projection mirror as adiverging beam may be provided.

In the aforementioned configuration, the laser beam in the scanned lightprojected by the projection mirror may enter the eyeball as a light beamthat is focused near the retina of the eyeball by a crystalline lens ofthe eyeball of the user.

The present invention is an image projection device characterized byincluding: a light source that emits a laser beam; a scanning unit thattwo-dimensionally scans the laser beam emitted from the light source; aprojection mirror that converges scanned light near a pupil of aneyeball of a user, and then projects the scanned light onto a retina ofthe eyeball of the user to project an image onto the retina, the scannedlight being composed of the laser beam that has been scanned by thescanning unit; and an optical means that allows a laser beam in thescanned light to enter the projection mirror as a diverging beam. Thepresent invention can provide a good image to a user.

In the aforementioned configuration, the laser beam in the scanned lightprojected by the projection mirror may enter the eyeball as a light beamthat is focused near the retina of the eyeball by a crystalline lens ofthe eyeball of the user.

In the aforementioned configuration, the projection mirror may include alens of glasses located in front of the eyeball of the user, the lensmay include a first lens portion and a second lens portion located inthis order from a side of the eyeball of the user, and a diffractionelement located between the first lens portion and the second lensportion, and the scanned light composed of the laser beam may enter thefirst lens portion from the side of the eyeball of the user, and is thenreflected at an opposite surface of the second lens portion from theeyeball of the user to be projected onto the retina of the eyeball ofthe user.

The present invention is a projection device characterized by including:a light source that emits a laser beam; and a projection mirror thatincludes a lens of glasses located in front of an eyeball of a user, andprojects the laser beam onto the eyeball of the user, wherein the lensincludes a first lens portion and a second lens portion located in thisorder from a side of the eyeball of the user, and a diffraction elementlocated between the first lens portion and the second lens portion, andthe laser beam enters the first lens portion from the side of theeyeball of the user, and is then reflected at an opposite surface of thesecond lens portion from the eyeball of the user to be projected ontothe eyeball of the user. The present invention can achieve both afunction as a projection mirror and a function as a lens of glasses.

Effects of the Invention

The present invention can provide a good image to a user. Or, thepresent invention can achieve both a function as a projection mirror anda function as a lens of glasses.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an image projection device in accordance with afirst embodiment viewed from above, and FIG. 1B illustrates the imageprojection device viewed from the side;

FIG. 2 illustrates the projections of red, green, and blue laser beamsby a projection mirror using a single-layer half mirror having acompositional structure of a free curved surface and a diffractionsurface;

FIG. 3 illustrates the projections of red, green, and blue laser beamsby a projection mirror using a multilayered half mirror having acompositional structure of a free curved surface and a diffractionsurface;

FIG. 4A through FIG. 4C illustrate the projection of the laser beam ontothe retina with respect to the move of the eyeball when the laser beamis converged near the pupil;

FIG. 5A through FIG. 5C illustrate the projection of the laser beam ontothe retina with respect to the move of the eyeball when the laser beamis converged at the retina side beyond the pupil, and when a horizontalincidence angle θ of the laser beam entering the eyeball is configuredto be equal to 90° or greater;

FIG. 6A through FIG. 6C illustrate the projection of the laser beam ontothe retina with respect to the move of the eyeball when the position ofthe scan range of the laser beam is changed within the operating rangeof a scanning mirror;

FIG. 7 illustrates a scan trajectory of the laser beam in raster scan bythe scanning mirror;

FIG. 8A through FIG. 8C illustrate results of simulation that calculatedthe scan trajectory of the laser beam projected onto the retina;

FIG. 9 illustrates corrected image data;

FIG. 10A and FIG. 10B illustrate a scan trajectory of the laser beam inraster scan by a scanning mirror of a third embodiment;

FIG. 11 illustrates corrected image data;

FIG. 12 illustrates an image projection device in accordance with afourth embodiment viewed from above;

FIG. 13A illustrates the projection of the laser beam onto the retinawhen the laser beam enters the projection mirror while being a parallelbeam, and FIG. 13B illustrates the projection of the laser beam onto theretina when the laser beam enters the projection mirror while being adiverging beam;

FIG. 14 illustrates an image projection device in accordance with afirst variation of the fourth embodiment viewed from above;

FIG. 15A is a top view illustrating a part of an image projection devicein accordance with a fifth embodiment, FIG. 15B is a top view thatenlarges a range A of FIG. 15A, and FIG. 15C is a top view that enlargesa range B of FIG. 15B; and

FIG. 16 is a cross-sectional view that enlarges a range C of FIG. 15C.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Hereinafter, a description will be given of embodiments of the presentinvention with reference to the drawings.

First Embodiment

FIG. 1A illustrates an image projection device in accordance with afirst embodiment viewed from above, and FIG. 1B illustrates the imageprojection device viewed from the side. In FIG. 1B, a part of a laserbeam 34 is not illustrated for clarity of illustration. As illustratedin FIG. 1A and FIG. 1B, a temple 10 of glasses includes a light source12 that emits the laser beam 34, and a scanning mirror 14 that functionsas a scanning unit that two-dimensionally scans the laser beam 34emitted from the light source 12. The light source 12 emits a laser beamof a single wavelength or a laser beam of different wavelengths. A lensand a mirror are used to allow the laser beam 34 emitted from the lightsource 12 to enter the scanning mirror 14, but they are not illustrated.

A controller 16 controls the emission of the laser beam 34 from thelight source 12 based on input image data. That is to say, the lightsource 12 converts an image signal to a laser beam. The controller 16may not be located in the glasses but may be located in an externaldevice, or may be located in the temple 10 of the glasses. Here, thecontroller 16 is located in an external device (e.g., a mobile terminal)as an example.

The scanning mirror 14 scans the laser beam 34 emitted from the lightsource 12 to use it as projection light for projecting an image onto theretina 26 of an eyeball 22 of the user. The scanning mirror 14 is, forexample, a MEMS (Micro Electro Mechanical Systems) mirror, and scans thelaser beam in horizontal and vertical directions.

The laser beam 34 that has been scanned by the scanning mirror 14(scanned light) is reflected toward a lens 20 of the glasses by a mirror18. A projection mirror 24 is located on the surface, located at theeyeball 22 side of the user, of the lens 20. The projection mirror 24projects the laser beam 34 that has been scanned by the scanning mirror14 (scanned light) onto the retina 26 of the eyeball 22 to project animage onto the retina 26. That is to say, the user can recognize theimage by the residual image effect of the laser beam projected onto theretina 26. The projection mirror 24 is designed so that the convergenceposition of the laser beam 34 that has been scanned by the scanningmirror 14 (scanned light) is at the retina 26 side beyond a pupil 28 ofthe eyeball 22.

When the light source 12 emits a laser beam of a single wavelength, theprojection mirror 24 may be a single-layer half mirror having a freecurved surface or a compositional structure of a free curved surface anda diffraction surface. By using the projection mirror 24 that has a freecurved surface, the laser beam 34 that has been scanned by the scanningmirror 14 can be projected onto the retina 26 of the eyeball 22 evenwhen the position of the scanning mirror 14 located in the temple 10 ofthe glasses deviates from the position of the eyeball 22 in the heightdirection. By using the projection mirror 24 that has a compositionalstructure of a free curved surface and a diffraction surface, the laserbeam 34 that has been scanned by the scanning mirror 14 can be reflectedat a steeper angle.

However, when the light source 12 emits a laser beam of differentwavelengths such as a red laser beam, a green laser beam, and a bluelaser beam, the user may not recognize a good image when a single-layerhalf mirror having a compositional structure of a free curved surfaceand a diffraction surface is used. This is because, since thediffraction angle changes with respect to each wavelength, theconvergence positions of the red laser beam, the green laser beam, andthe blue laser beam greatly deviate from each other, and thereby theprojection positions of them onto the retina 26 deviate from each other.The wavelength of the red laser beam ranges from 610 to 660 nm, thewavelength of the green laser beam ranges from 515 to 540 nm, and thewavelength of the blue laser beam ranges from 440 to 460 nm, forexample. The example of the light source emitting the red, green, andblue laser beams is a light source in which laser diode chips of RGB(Red, Green, and Blue), a three color multiplexer, and a microcollimator lens are integrated.

FIG. 2 illustrates the projections of the red, green, and blue laserbeams by the projection mirror 24 using a single-layer half mirrorhaving a compositional structure of a free curved surface and adiffraction surface. In FIG. 2, the red laser beam is indicated by thesolid line, the green laser beam is indicated by the dashed line, andthe blue laser beam is indicated by the chain line. As illustrated inFIG. 2, the diffraction angles at the projection mirror 24 of the red,green, and blue laser beams differ from each other. Thus, theconvergence positions of the red, green, and blue laser beams greatlydiffer from each other. For example, when the projection mirror 24 isdesigned based on the convergence position of the green laser beam(dashed line), the convergence positions of the red laser beam (solidline) and the blue laser beam (chain line) greatly deviate from that ofthe green laser beam (dashed line). Therefore, the projection positionsof the red, green, and blue laser beams onto the retina 26 differ fromeach other, and the user thereby cannot recognize a good image.

To avoid such a situation, the projection mirror 24 preferably employs amultilayered half mirror in which two or more wavelength selective filmswith a free curved surface are stacked, and each layer preferably has anappropriate diffraction surface. FIG. 3 illustrates the projections ofthe red, green, and blue laser beams by the projection mirror 24 using amultilayered half mirror having a compositional structure of a freecurved surface and a diffraction surface. In FIG. 3, the red laser beamis indicated by the solid line, the green laser beam is indicated by thedashed line, and the blue laser beam is indicated by the chain line. Asillustrated in FIG. 3, when the projection mirror 24 employs amultilayered half mirror in which three wavelength selective films, eachhaving a free curved surface, are stacked, and the layers have thediffraction surfaces that reflect the red, green, and blue laser beamsin appropriate directions, the projection positions of the red, green,and blue laser beams onto the retina 26 can become the same. This allowsthe user to recognize a good color image.

A description will now be given of a reason why the convergence positionof the laser beam 34 that has been scanned by the scanning mirror 14(scanned light) is configured to be at the retina 26 side beyond thepupil 28 as explained in FIG. 1A and FIG. 1B. FIG. 4A through FIG. 4Cillustrate the projection of the laser beam 34 onto the retina 26 withrespect to the move of the eyeball 22 when the laser beam 34 isconverged near the pupil 28. FIG. 4A illustrates a case where theeyeball 22 faces the front, FIG. 4B illustrates a case where the eyeball22 looks leftward from the front, and FIG. 4C illustrates a case wherethe eyeball 22 looks further leftward.

Assume that the laser beam 34 is converged near the center of the pupil28 and then projected onto the retina 26 when the eyeball 22 faces thefront as illustrated in FIG. 4A. In this case, when the eyeball 22 looksleftward, the laser beam 34 is converged near the edge of the pupil 28and projected onto the retina 26 as illustrated in FIG. 4B. When theeyeball 22 looks further leftward, the laser beam 34 fails to enter thepupil 28 and fails to be projected onto the retina 26 as illustrated inFIG. 4C. As described above, depending on the rotation angle of theeyeball 22, the laser beam 34 is not projected onto the retina 26, andthe user can not recognize an image.

Thus, to reduce the missing of an image due to the move of the eyeball22, the convergence position of the laser beam 34 by the projectionminor 24 is configured to be at the retina 26 side beyond the pupil 28.In addition, to reduce the missing of an image, the operating range ofthe scanning mirror 14 is extended to increase the incidence angles ofthe laser beam 34 entering the eyeball 22 in the horizontal and verticaldirections to, for example, 90° or greater.

FIG. 5A through FIG. 5C illustrate the projection of the laser beam 34onto the retina 26 with respect to the move of the eyeball 22 when thelaser beam 34 is converged at the retina 26 side beyond the pupil 28,and the incidence angle of the laser beam 34 entering the eyeball 22 isconfigured to be equal to 90° or greater. FIG. 5A illustrates a casewhere the eyeball 22 faces the front, FIG. 5B illustrates a case wherethe eyeball 22 looks leftward from the front, and FIG. 5C illustrates acase where the eyeball 22 looks further leftward.

Assume that the laser beam 34 is converged at a position located at theretina 26 side viewed from near the center of the pupil 28, enters theeyeball 22 at the horizontal incidence angle θ of 90° or greater, and isprojected onto the retina 26 when the eyeball 22 faces the front asillustrated in FIG. 5A. In this case, even when the eyeball 22 looksleftward, a part of the laser beam 34 is projected onto the retina 26 asillustrated in FIG. 5B and FIG. 5C, and the missing of an image is thusreduced. The same is applicable to a case where the eyeball 22 moves inthe vertical direction. As described above, when the laser beam 34 thathas been scanned by the scanning mirror 14 (scanned light) is convergedat the retina 26 side beyond the pupil 28, and the incidence angle ofthe laser beam 34 entering the eyeball 22 is increased, the missing ofan image due to the move of the eyeball 22 is reduced. However, thisdoes not completely reduce the missing of a part of an image.

The inventors have found a method of reducing the missing of an image byscanning the laser beam 34 with use of a part of the operating range ofthe scanning minor 14 while the operating range of the scanning minor 14is extended to increase the incidence angle of the laser beam 34entering the eyeball 22 (to, for example, 90° or greater). That is tosay, the inventors have found a method that does not scan the laser beam34 by using all the operating range within which the scanning minor 14operates laterally and vertically, but scans the laser beam 34 by usinga part of the operating range in the lateral and vertical directions.That is to say, while the scanning minor 14 operates laterally andvertically within the operating range, the controller 16 controls thelight source 12 to emit the laser beam 34 only when the scanning minor14 is operating within a range that is a part of the operating range.

When the range with which the laser beam 34 is scanned is changed withinthe operating range of the scanning mirror 14, the position of the laserbeam 34 projected onto the retina 26 changes. Thus, when the position ofthe scan range of the laser beam 34 is changed in accordance with themove of the eyeball 22, all of the laser beam 34 that has been scanned(scanned light) can be projected onto the retina 26 even when theeyeball 22 has moved. This will be explained with use of FIG. 6A throughFIG. 6C. FIG. 6A through FIG. 6C illustrate the projection of the laserbeam 34 onto the retina 26 with respect to the move of the eyeball 22when the position of the scan range of the laser beam 34 is changedwithin the operating range of the scanning mirror 14. FIG. 6Aillustrates a case where the eyeball 22 faces the front, FIG. 6Billustrates a case where the eyeball 22 looks leftward from the front,and FIG. 6C illustrates a case where the eyeball 22 looks furtherleftward.

Assume that the laser beam 34 is scanned near the center of theoperating range of the scanning mirror 14 and projected onto near thecenter of the retina 26 when the eyeball 22 faces the front asillustrated in FIG. 6A. When the eyeball 22 looks leftward, the laserbeam 34 can be projected onto the retina 26 by scanning the laser beam34 in a region shifted from near the center of the operating range ofthe scanning mirror 14 in the direction corresponding to the move of theeyeball 22 as illustrated in FIG. 6B. When the eyeball 22 looks furtherleftward, the laser beam 34 can be projected onto the retina 26 byscanning the laser beam 34 in a region further shifted from near thecenter of the operating range of the scanning mirror 14 as illustratedin FIG. 6C.

As described above, the missing of an image projected onto the retina 26can be reduced and a good image can be provided to the user by scanningthe laser beam 34 emitted from the light source 12 by using a part ofthe operating range of the scanning mirror 14. For example, the missingof an image projected onto the retina 26 is reduced by scanning thelaser beam 34 emitted from the light source 12 in different positionswithin the operating range of the scanning mirror 14 in accordance withthe move of the eyeball 22.

To scan the laser beam 34 in different positions within the operatingrange of the scanning mirror 14 in accordance with the move of theeyeball 22 of the user, the user may operate a mobile terminal includingthe controller 16, and the controller 16 may control the emission of thelaser beam 34 from the light source 12 based on the operation.Alternatively, a well-known device detecting the move of the eyeball 22may be provided, and the controller 16 may control the emission of thelaser beam 34 from the light source 12 based on the feedback from thedevice.

To allow the laser beam 34 to be projected onto the retina 26 even whenthe eyeball 22 broadly moves, the incidence angle of the laser beam 34,which is scanned within the operating range of the scanning minor 14, tothe eyeball 22 of the user by the projection minor 24 is preferablylarge. For example, the incidence angle to the eyeball 22 in thehorizontal direction is preferably equal to 70° or greater, is morepreferably equal to 80° or greater, is yet more preferably equal to 90°or greater, and is further preferably equal to 100° or greater. Theincidence angle to the eyeball 22 in the vertical direction ispreferably equal to 60° or greater, is more preferably equal to 70° orgreater, is yet more preferably 90° or greater, and is furtherpreferably equal to 100° or greater.

Second Embodiment

The configuration of an image projection device in accordance with asecond embodiment is the same as that of the first embodimentillustrated in FIG. 1, and thus the description thereof is omitted. Amethod called raster scan is used to project an image onto the retina 26by scanning the laser beam 34 by the scanning mirror 14. FIG. 7illustrates a scan trajectory of the laser beam in raster scan by thescanning mirror 14. As illustrated in FIG. 7, in raster scan, an imageis displayed by scanning the laser beam from the upper left to the lowerright of the image at high speed. Thus, simulated were the scantrajectory of the laser beam projected onto the retina 26 by scanningthe laser beam by raster scan.

FIG. 8A through FIG. 8C illustrate results of the simulation thatcalculated the scan trajectory of the laser beam 34 projected onto theretina 26. FIG. 8A through FIG. 8C illustrate simulation results whenthe eyeball 22 faces the front. The horizontal axis represents adistance [mm] from the center of the retina 26 in the lateral direction,and the vertical axis represents a distance [mm] from the center of theretina 26 in the longitudinal direction. FIG. 8A illustrates thesimulation result of the scan trajectory when the laser beam is scannedonly in the horizontal direction in five positions between which theinterval is constant in the vertical direction. FIG. 8B illustrates thesimulation result of the scan trajectory when the laser beam is scannedonly in the vertical direction in seven positions between which theinterval is constant in the horizontal direction. FIG. 8C is formed byoverlapping FIG. 8A with FIG. 8B.

FIG. 8A through FIG. 8C reveal that, when an image is projected onto theretina 26 by scanning the laser beam 34 emitted based on image data ofan rectangle image, the image projected onto the retina 26 does notbecome a rectangle image but becomes an inclined trapezoidal image. Thatis to say, an image of which the height gradually changes from one of apair of vertical sides to the other one is projected onto the retina 26.FIG. 8B and FIG. 8C reveal that the inclined trapezoidal image projectedonto the retina 26 is an image of which the curvature graduallyincreases from the shorter side to the longer side of the verticalsides. This reveals that it is difficult for the user to see a goodimage even when the missing of an image is reduced by scanning the laserbeam 34 by using a part of the operating range of the scanning mirror14. Thus, the second embodiment describes an image projection devicecapable of projecting a good image on the retina 26.

As described above, when an image is projected onto the retina 26 byscanning the laser beam 34 emitted based on image data of a rectangleimage, an inclined trapezoidal image of which the curvature graduallyincreases from the shorter side to the longer side of the vertical sidesis projected. That is to say, when the laser beam is emitted based onimage data of an image obtained by correcting the image obtained fromFIG. 8C reversely, the rectangle image in which the curvature iscorrected can be projected onto the retina 26. That is to say, a goodimage with reduced distortion can be projected by emitting a laser beambased on image data of an image that has a shape obtained by rotating aninclined trapezoidal shape obtained from FIG. 8C by 180° and to whichthe curvature that cancels out the curvature obtained from FIG. 8C isapplied.

Thus, in the second embodiment, the controller 16 generates correctedimage data 40 by gradually changing the height of the image of the inputimage data from one vertical side to the other vertical side andgradually changing the curvature of the image from one vertical side tothe other vertical side as illustrated in FIG. 9. The controller 16 thencontrols the light source 12 to emit the laser beam 34 based on thecorrected image data 40. This enables to project a good image withreduced distortion onto the retina 26, and enables to provide a goodimage to the user.

As illustrated in FIG. 1, when the scanning mirror 14 is located at theleft of the eyeball 22, the controller 16 preferably generates correctedimage data in which an image has a quadrangle shape of which the leftvertical side is longer than the right vertical side, and in which thecurvature of the image toward the longer side gradually increases fromthe longer side to the shorter side of the vertical sides as illustratedin FIG. 9. When the scanning mirror 14 is located at the right of theeyeball 22, the controller 16 preferably generates corrected image datain which an image has a quadrangle shape of which the right verticalside is longer than the left vertical side, and in which the curvatureof the image toward the longer side gradually increases from the longerside to the shorter side of the vertical sides.

Third Embodiment

A third embodiment is another embodiment capable of projecting a goodimage with reduced distortion onto the retina 26. The third embodimentdiffers from the first embodiment and the second embodiment in thescanning mirror 14, and uses the scanning mirror 14 describedhereinafter. FIG. 10A and FIG. 10B illustrate a scan trajectory of thelaser beam in raster scan by the scanning mirror 14 of the thirdembodiment. As illustrated in FIG. 10A, the third embodiment uses thescanning mirror 14 of which the scanning amplitude in the horizontaldirection is not constant in the vertical direction and graduallydecreases in the vertical direction. To modulate the scanning amplitudein the horizontal direction in such a manner, voltage applied to thescanning mirror 14 is changed.

The aforementioned scanning mirror 14 is rotated by, for example, 90°with respect to the scanning mirror 14 of the first embodiment and thesecond embodiment, and then mounted. This makes it possible to obtainthe scanning mirror 14 of which the scanning amplitude in the verticaldirection gradually decreases in the horizontal direction as illustratedin FIG. 10B. The mounting angle of the scanning mirror 14 is not limitedto 90°, and may be an angle near 90°. For example, the scanning mirror14 may be rotated by 85° to 95°, or may be rotated by 80° to 100°. Otherconfigurations of the third embodiment are the same as those of thefirst embodiment illustrated in FIG. 1, and thus the description thereofis omitted.

The use of the scanning mirror 14 described in FIG. 10A and FIG. 10B canprevent the projection of an inclined trapezoidal image described inFIG. 8A onto the retina 26 even when the laser beam is emitted based onimage data of a rectangle image. However, this cannot completely preventthe curvature of an image described in FIG. 8B.

Thus, the third embodiment generates corrected image data describedhereinafter and makes the light source 12 emit the laser beam 34 basedon the corrected image data in addition to rotating the scanning mirror14 of which the scanning amplitude in the horizontal direction graduallychanges in the vertical direction to use it. That is to say, thecontroller 16 generates corrected image data 50 by rotating the image ofthe input image data, and gradually changing the curvature of the imagefrom one vertical side to the other vertical side as illustrated in FIG.11. The controller 16 controls the light source 12 to emit the laserbeam 34 based on the corrected image data 50. This enables to project agood image with reduced distortion onto the retina 26, and enables toprovide a good image to the user. To project the correct image onto theretina 26, the scanning mirror 14 is preferably rotated in the samedirection and by approximate the same angle as the image of the inputimage data is rotated. For example, when the scanning mirror 14 isrotated by 90°, the image of the input image data is preferably rotatedby 90° in the direction same as the rotation direction of the scanningmirror 14.

Also in the third embodiment, as with in the second embodiment, when thescanning mirror 14 is located at the left of the eyeball 22, thecontroller 16 preferably generates corrected image data in which thecurvature toward the left vertical side gradually increases from theleft vertical side to the right vertical side. On the other hand, whenthe scanning mirror 14 is located at the right of the eyeball 22, thecontroller 16 preferably generates corrected image data in which thecurvature toward the right vertical side gradually increases from theright vertical side to the left vertical side.

Fourth Embodiment

FIG. 12 illustrates an image projection device in accordance with afourth embodiment viewed from above. Unlike FIG. 1A, a single laser beam(a laser beam) having a finite light beam diameter is illustratedenlarged in FIG. 12. As illustrated in FIG. 12, in the image projectiondevice of the fourth embodiment, the light source 12 is not mounted inthe temple 10 of the glasses and is separately located, and the laserbeam 34 emitted from the light source 12 is introduced through anoptical fiber 60 and enters the scanning mirror 14. A condensing lens 62is located in the light path of the laser beam 34 between the opticalfiber 60 and the scanning mirror 14 and in the temple 10 of the glasses.Other configurations are the same as those of the first embodimentillustrated in FIG. 1A and FIG. 1B, and thus the description thereof isomitted.

Here, a description will be given of the difference in the laser beam 34projected onto the retina 26 of the eyeball 22 between a case where thelaser beam 34 in the scanned light enters the projection mirror 24 whilebeing a parallel beam and a case where it enters while being a divergingbeam. FIG. 13A illustrates the projection of the laser beam 34 onto theretina 26 when the laser beam 34 enters the projection mirror 24 whilebeing a parallel beam, and FIG. 13B illustrates the projection of thelaser beam 34 onto the retina 26 when the laser beam 34 enters whilebeing a diverging beam.

As illustrated in FIG. 13A, the scanned light composed of the laser beam34 that has been scanned by the scanning mirror 14 is converged near thepupil 28 by the projection mirror 24 to pass through the pupil 28 asdescribed in FIG. 6A through FIG. 6C described above. The convergencerange of the scanned light near the pupil 28 is preferably a range witha diameter of approximately 2 mm, for example. When the laser beam 34 inthe scanned light enters the projection mirror 24 while being a parallelbeam, the laser beam 34 is also focused near the pupil 28 by theprojection mirror 24 having such a condensing power. When the laser beam34 is focused near the pupil 28, it is projected onto the retina 26 as adiverging beam. This increases the beam spot size of the laser beam 34projected onto the retina 26, and a somewhat defocused image may beprojected onto the retina 26.

On the other hand, when the laser beam 34 is focused before theprojection mirror 24 as illustrated in FIG. 13B, and enters theprojection mirror 24 while being a diverging beam, the laser beam 34 canenter the eyeball 22 while being a parallel beam by the condensing powerof the projection mirror 24. The laser beam 34 entering the eyeball 22as a parallel beam is focused near the retina 26 by a crystalline lens64. This allows the beam spot size of the laser beam 34 projected ontothe retina 26 to be a proper size. The size of the laser beam 34 when itenters the projection mirror 24 is preferably small so that the diameterof the laser beam 34 when it enters the eyeball 22 is thinner than thepupil 28.

The image projection device of the fourth embodiment includes, asillustrated in FIG. 12, the condensing lens 62 that focuses the laserbeam 34 emitted from the optical fiber 60. Thus, the laser beam 34emitted from the optical fiber 60 is converted to a convergent beam bythe condensing lens 62. An appropriate lens is selected for thecondensing lens 62 so that the laser beam 34 is converted to aconvergent beam that is focused between the scanning mirror 14 and theprojection mirror 24. This allows the laser beam 34 in the scanned lightto enter the projection mirror 24 while being a diverging beam. Thus, asdescribed in FIG. 13B, the beam spot size of the laser beam 34 projectedonto the retina 26 can become a proper size.

As described above, the fourth embodiment provides the condensing lens62 (an optical means) that allows the laser beam 34 in the scanned lightto enter the projection mirror 24 as a diverging beam. This allows thelaser beam 34 to enter the eyeball 22 as a light beam (e.g., a parallelbeam) that is focused near the retina 26 by the crystalline lens 64 ofthe eyeball 22 of the user as described in FIG. 13B. Thus, the beam spotsize of the laser beam 34 projected onto the retina 26 can become aproper size, and a good image can be provided to the user.

The fourth embodiment provides the condensing lens 62 as an opticalmeans as illustrated in FIG. 12. However, instead of the condensing lens62, a diverging lens that allows the laser beam 34 in the scanned lightto enter the projection mirror 24 as a diverging beam with a smalldiameter may be provided.

FIG. 14 illustrates an image projection device in accordance with afirst variation of the fourth embodiment viewed from above. As with inFIG. 12, a single laser beam (a laser beam) is illustrated enlarged inFIG. 14. As illustrated in FIG. 14, the first variation of the fourthembodiment differs from the fourth embodiment in that a collimator lens66 is located in the temple 10 of the glasses instead of the condensinglens, and in that a concave mirror 68 is located in the light path ofthe scanned light between the scanning minor 14 and the projection minor24.

In the image projection device of the first variation of the fourthembodiment, the laser beam 34 emitted from the optical fiber 60 isconverted to a parallel beam by the collimator lens 66, and then entersthe scanning minor 14. The scanned light composed of the laser beam 34that has been scanned by the scanning mirror 14 enters the concave minor68. Thus, the laser beam 34 in the scanned light is converted to aconvergent beam that is focused before the projection minor 24 by theconcave mirror 68, and then enters the projection minor 24 as adiverging beam. An appropriate mirror is selected for the concave minor68 so that the laser beam 34 in the scanned light is focused before theprojection minor 24 as described above. This allows the laser beam 34 inthe scanned light to enter the eyeball 22 as a light beam (e.g., aparallel beam) that is focused near the retina 26 by the crystallinelens 64 of the eyeball 22 of the user as with in the fourth embodiment.Thus, the beam spot size of the laser beam 34 projected onto the retina26 can become a proper size, and a good image can be provided to theuser.

In the first variation of the fourth embodiment, the concave mirror 68is provided as an optical means, but a convex mirror that allows thelaser beam 34 in the scanned light to enter the projection minor 24 as adiverging beam with a small diameter may be provided instead of theconcave mirror 68.

As described in the fourth embodiment and the first variation of thefourth embodiment, the optical means that allows the laser beam 34 inthe scanned light to enter the projection mirror 24 as a diverging beammay be located in the light path of the laser beam 34 before reachingthe scanning mirror 14, or may be located in the light path of thescanned light composed of the laser beam 34 that has been scanned by thescanning mirror 14. The above described case where the laser beam 34entering the eyeball 22 is a parallel beam is not limited to a casewhere the laser beam 34 is a complete parallel beam, and includes a casewhen the laser beam 34 is a parallel beam that can be focused on theretina 26 by the crystalline lens 64.

Fifth Embodiment

The first embodiment provides the projection minor 24 made of a halfmirror having a compositional structure of a free curved surface and adiffraction surface, which is a structure designed to have a reflectivediffraction surface located on the curved surface, on the surface of thelens 20 of the glasses at the eyeball 22 side as illustrated in FIG. 1through FIG. 3. However, in this case, the projection mirror 24 that isproperly designed may have difficulty in being placed on the eyeball 22side surface of the lens 20. That is to say, the structure where theprojection mirror 24 is located on the eyeball 22 side surface of thelens 20 may have difficulty in achieving both the function as aprojection mirror that projects the laser beam 34 onto the retina 26 ofthe eyeball 22 and the function as a lens of the glasses that providesthe sight of the object through the lens 20. The diffraction elementlocated in the projection mirror 24 has inhomogeneous pitch intervals toproject the laser beam 34 onto the retina 26. Thus, the diffractionelement that has unequal pitches and is axial asymmetry is drawn andprocessed on the curved surface. In a part having a large diffractionangle, the pitch interval of the diffraction element is decreased to anapproximate wavelength. Thus, the manufacture of the projection mirror24 is difficult. Thus, the fifth embodiment describes a case that canachieve both the function as a projection mirror and the function as alens of glasses.

FIG. 15A is a top view illustrating a part of the image projectiondevice in accordance with the fifth embodiment, FIG. 15B is a top viewthat enlarges a range A of FIG. 15A, and FIG. 15C is a top view thatenlarges a range B of FIG. 15B. FIG. 16 is a cross-sectional view thatenlarges a range C of FIG. 15C. In FIG. 15A through FIG. 15C, a singlelaser beam (a laser beam) having a finite light beam diameter isillustrated enlarged as with in FIG. 12 of the fourth embodiment.

As illustrated in FIG. 15A through FIG. 16, a lens 20 a of glassesincludes a first lens portion 70 and a second lens portion 72 in thisorder from the eyeball 22 side, and a transmissive diffraction element74 is located between the first lens portion 70 and the second lensportion 72. The first lens portion 70 and the second lens portion 72 maybe made of the same glass material or made of different glass materials.The material is appropriately selected in consideration of theperformance of the glasses lens and the performance of the diffractionelement. The first lens portion 70 and the second lens portion 72 mayadhere with each other across the diffraction element 74, or an airlayer 76 may be located at one side of the diffraction element 74 asillustrated in FIG. 16. This increases the degree of freedom of themethod of manufacturing the diffraction element 74. In FIG. 16, theupper surface of the first lens portion 70 is a plane surface, andrecesses and protrusions are formed on the lower surface of the secondlens portion 72, but the lower surface of the second lens portion 72 maybe a plane surface and recesses and protrusions may be formed on theupper surface of the first lens portion 70.

The diffraction element 74 linearly extends in a direction parallel tothe pupil 28 in a state where the eyeball 22 faces the front forexample. The diffraction element 74 may extend while being tilted withrespect to the pupil 28 in a state where the eyeball 22 faces the front.For example, in consideration of the diffraction angle, the diffractionelement 74 may extend while being tilted so that the diffraction element74 is closer to the opposite surface of the lens 20 a from the eyeball22 at the side that the laser beam 34 enters (the left side in FIG. 15A)and is closer to the eyeball 22 side surface of the lens 20 a at theside opposite to the side that the laser beam 34 enters (the right sidein FIG. 15A). The diffraction element 74 may be located across theentire of the lens 20 a, or may be located within a range ofapproximately 20 mm×20 mm.

The opposite surface of the second lens portion 72 from the eyeball 22is coated with, for example, a reflection film 78. The details will bedescribed later, but the lens 20 a and the reflection film 78 functionas a projection mirror 24 a that projects the laser beam 34 that hasbeen scanned by the scanning mirror (scanned light) onto the retina 26of the eyeball 22 to project an image onto the retina 26. That is tosay, in the fifth embodiment, a half mirror is not located on theeyeball 22 side surface of the first lens portion 70 unlike the firstthrough fourth embodiments. Other configurations are the same as thoseof the fourth embodiment illustrated in FIG. 12, and thus thedescription thereof is omitted.

A description will next be given of the light path through which thelaser beam 34 emitted from the light source 12 reaches the retina 26 ofthe eyeball 22 with use of FIG. 12 and FIG. 15A through FIG. 15C. Asdescribed in FIG. 12 of the fourth embodiment, the laser beam 34 emittedfrom the light source 12 and introduced through the optical fiber 60 isconverted into a convergent beam by the condensing lens 62, and thenscanned by the scanning mirror 14. An appropriate lens is selected forthe condensing lens 62 so that the laser beam 34 is converted into aconvergent beam that is focused between the scanning mirror 14 and thelens 20 a. This allows the laser beam 34 in the scanned light to enterthe lens 20 a while being a diverging beam.

The laser beam 34 in the scanned light enters the first lens portion 70located at the eyeball 22 side of the lens 20 a from the eyeball 22side. When entering the first lens portion 70, the laser beam 34 isrefracted in, for example, the thickness direction of the first lensportion 70. The laser beam 34 that has entered the first lens portion 70passes through the diffraction element 74, and then enters the secondlens portion 72. When entering the second lens portion 72, the laserbeam 34 is refracted in, for example, the thickness direction of thesecond lens portion 72. The reflection film 78 located on the oppositesurface of the second lens portion 72 from the eyeball 22 has acharacteristic that selectively reflects light with the wavelength ofthe laser beam 34, and has a characteristic that passes the most (e.g.,approximately 95%) of the laser beam 34, but reflects a part (e.g.,approximately 5%) thereof. Therefore, a part of the laser beam 34 thathas entered the second lens portion 72 is reflected at the oppositesurface of the second lens portion 72 from the eyeball 22. The reflectedlaser beam 34 passes through the diffraction element 74 and the firstlens portion 70, and is emitted from the first lens portion 70. Thelaser beam 34 emitted from the first lens portion 70 passes through thepupil 28 and the crystalline lens 64 of the eyeball 22, and is projectedonto the retina 26.

According to the fifth embodiment, as illustrated in FIG. 15A throughFIG. 15C, the lens 20 a included in the projection mirror 24 a includesthe first lens portion 70 and the second lens portion 72 located in thisorder from the eyeball 22 side of the user, and the diffraction element74 located between the first lens portion 70 and the second lens portion72. The scanned light composed of the laser beam 34 enters the firstlens portion 70 from the eyeball 22 side of the user, is then reflectedat the opposite surface of the second lens portion 72 from the eyeball22 of the user, and is projected onto the retina 26 of the eyeball 22 ofthe user. The aforementioned configuration enables to achieve thefunction as a projection mirror that projects the scanned light composedof the laser beam 34 onto the retina 26 of the eyeball 22 and thefunction as a lens of glasses that provides the sight of the objectthrough the lens 20 a. For example, when the transmission factor and thereflectance of the opposite surface of the second lens portion 72 fromthe eyeball 22 are properly configured and the diffraction efficiency ofthe diffraction element 74 is properly configured, both the function asa projection mirror (a component for the image projection device) andthe function as a lens of glasses can be achieved.

As illustrated in FIG. 16, the diffraction element 74 preferably has aplanar diffraction surface between the first lens portion 70 and thesecond lens portion 72. This eases the manufacture of the diffractionelement 74. When the projection mirror 24 is located on the eyeball 22side surface of the lens 20 as described in the first embodiment, thepitch interval of the diffraction element is small in a part where thediffraction angle is large as described above. On the other hand, in thefifth embodiment, the pitch interval of the diffraction element 74 canbe prevented from decreasing because of the following reasons. The firstreason is as follows. The laser beam 34 is refracted in the thicknessdirection of the first lens portion 70 and then enters the first lensportion 70, and the incidence angle to the diffraction element 74thereby decreases. Thus, the diffraction power of the diffractionelement 74 can be reduced. The second reason is as follows. In glassessuch as glasses for short-sight, glasses for distance vision, andreading glasses, the second lens portion 72 generally has a convex shapetoward the opposite side of the eyeball 22, and the opposite surface ofthe second lens portion 72 from the eyeball 22 is a concave with respectto the laser beam 34. Thus, the effect that converts the laser beam 34to a convergent beam acts, and this also reduces the diffraction powerof the diffraction element 74. The third reason is as follows. The laserbeam 34 passes through the diffraction element 74 twice, and this alsoreduces the diffraction power of the diffraction element 74. Therefore,the decrease in the pitch interval of the diffraction element 74 isreduced, and this also eases the manufacture.

In FIG. 15A through FIG. 15C, the reflection film 78 is located on theopposite surface of the second lens portion 72 from the eyeball 22, andthe laser beam 34 is reflected by the reflection film 78. However, thisdoes not intend to suggest any limitation. As long as the laser beam 34is reflected at the opposite surface of the second lens portion 72 fromthe eyeball 22, the reflection film 78 may not be located on theopposite surface of the second lens portion 72 from the eyeball 22.

When the light source 12 emits a laser beam of a single wavelength, asingle diffraction element 74 is only required as illustrated in FIG.15A through FIG. 16, but when a laser beam of different wavelengths(e.g., red, green, and blue laser beams) is emitted, the aforementionedconfiguration is not sufficient because the diffraction angle changeswith respect to each wavelength as described above. In this case, thediffraction elements 74 each suitable for the corresponding one of thelaser beams of different wavelengths may be stacked in the lens 20 a.

In the fifth embodiment, the scanned light composed of the laser beam 34that has been scanned by the scanning mirror 14 is projected onto theretina 26 of the eyeball 22 by the projection mirror 24 a including thelens 20 a, and the image is projected on the retina 26. However, thisdoes not intend to suggest any limitation, and the projection device maybe a projection device in which the laser beam emitted from a lightsource is projected onto the eyeball 22 by the projection mirror 24 aincluding the lens 20 a. For example, the present invention can beapplied to a case where the laser beam is projected onto the retina orthe iris of the eyeball for the eye examination or the eye treatment.

In the first through third embodiments, the light source 12 and thescanning mirror 14 are located outside the temple 10 of glasses, but maybe located inside the temple 10 by widening the width of the temple 10of glasses. In the first through third embodiments, the light source 12is located in the temple 10 of glasses, but the light source 12 may belocated separately from glasses as with in the fourth and fifthembodiments. In the fourth and fifth embodiments, the light source 12may be located in the temple 10 of glasses as with in the first throughthird embodiments.

In the first through fifth embodiments, the scanning mirror 14 (e.g., aMEMS mirror) is employed as a scanning unit that two-dimensionally scansthe laser beam, but other components such as potassium tantalate niobate(KTN) crystal, which is an electro-optical material, may be employed aslong as it can two-dimensionally scan the laser beam. In the firstthrough fifth embodiments, an image is projected onto the retina 26 ofone eyeball 22, but the present invention can be applied to a case whenan image is projected onto the retinas 26 of both eyeballs 22.

Although the desirable embodiments of the present invention has beendescribed in detail, the present invention is not limited to a certainembodiment, and it should be understood that the various change,substitutions, and alterations could be made hereto without departingfrom the spirit and scope of the invention.

1. An image projection device comprising: a light source that emits a laser beam; a scanning unit that two-dimensionally scans the laser beam emitted from the light source; and a projection mirror that projects scanned light onto a retina of an eyeball of a user to project an image onto the retina, the scanned light being composed of the laser beam that has been scanned by the scanning unit, wherein the laser beam emitted from the light source is scanned by using a part of an operating range of the scanning unit.
 2. The image projection device according to claim 1, wherein a first range in the projection mirror corresponding to the operating range of the scanning unit when the user looks in a first direction is the same as a second range in the projection mirror corresponding to the operating range of the scanning unit when the user looks in a second direction different from the first direction, the laser beam is scanned in a first region of the operating range of the scanning unit when the user looks in a first direction, and the laser beam is scanned in a second region of the operating range of the scanning unit when the user looks in the second direction, the second region differing from the first region.
 3. The image projection device according to claim 1, wherein the scanned light enters the projection mirror from a side of the eyeball of the user, the projection mirror being located in front of the eyeball of the user, and the image projection device further comprises a controller that generates corrected image data by gradually decreasing height of an image of input image data from a first vertical side to a second vertical side opposite to the first vertical side and gradually increasing curvature toward the first vertical side of the image from the first vertical side to the second vertical side, and controls the light source to emit the laser beam based on the corrected image data, the first vertical side corresponding to a side at which the scanned light enters the projection mirror in a pair of vertical sides corresponding to a vertical direction of the projection mirror.
 4. The image projection device according to claim 1, wherein the scanned light enters the projection mirror from a side of the eyeball of the user, the projection mirror being located in front of the eyeball of the user, a scanning amplitute of the scanning unit in a first direction corresponding to a vertical direction of the projection mirror gradually decreases in a second direction from a first side at which the laser beam enters the projection mirror to a second side opposite to the first side in a horizontal direction of the projection mirror by rotating the scanning unit of which a scanning amplitute in a horizontal direction gradually changes in a vertical direction to use the scanning unit, and the image projection device further comprises a controller that generates corrected image data by rotating an image of input image data and gradually increasing curvature toward a first vertical side of the image from the first vertical side to a second vertical side opposite to the first vertical side, and controls the light source to emit the laser beam based on the corrected image data, the first vertical side corresponding to a side at which the scanned light enters the projection mirror in a pair of vertical sides corresponding to a vertical direction of the projection mirror.
 5. The image projection device according to claim 1, wherein the scanned light is converged at a side of the retina beyond a pupil of the eyeball of the user by the projection mirror.
 6. The image projection device according to claim 1, wherein the projection mirror has a compositional structure of a free curved surface and a diffraction surface.
 7. The image projection device according to claim 1, further comprising: an optical means that is located in a light path of the scanned light between the scanning unit and the projection mirror, and allows a laser beam in the scanned light to enter the projection mirror as a diverging beam, wherein the laser beam in the scanned light travels from the scanning unit in a direction away from the projection mirror, and is then reflected by the optical means to enter the projection mirror as a diverging beam.
 8. The image projection device according to claim 7, wherein the laser beam in the scanned light projected by the projection mirror enters the eyeball as a light beam that is focused near the retina of the eyeball by a crystalline lens of the eyeball of the user.
 9. An image projection device comprising: a light source that emits a laser beam; a scanning unit that two-dimensionally scans the laser beam emitted from the light source; a projection mirror that converges scanned light near a pupil of an eyeball of a user, and then projects the scanned light onto a retina of the eyeball of the user to project an image onto the retina, the scanned light being composed of the laser beam that has been scanned by the scanning unit; and an optical means that is located in a light path of the scanned light between the scanning unit and the projection mirror, and allows a laser beam in the scanned light to enter the projection mirror as a diverging beam, wherein the laser beam in the scanned light travels from the scanning unit in a direction away from the projection mirror, and is then reflected by the optical means to enter the projection mirror as a diverging beam.
 10. The image projection device according to claim 9, wherein the laser beam in the scanned light projected by the projection mirror enters the eyeball as a light beam that is focused near the retina of the eyeball by a crystalline lens of the eyeball of the user.
 11. The image projection device according to claim 1, wherein the projection mirror includes a lens of glasses located in front of the eyeball of the user, the lens includes a first lens portion and a second lens portion located in this order from a side of the eyeball of the user, and a diffraction element located between the first lens portion and the second lens portion, and the scanned light composed of the laser beam enters the first lens portion from the side of the eyeball of the user, and is then reflected at an opposite surface of the second lens portion from the eyeball of the user to be projected onto the retina of the eyeball of the user.
 12. A projection device comprising: a light source that emits a laser beam; and a projection mirror that includes a lens of glasses located in front of an eyeball of a user, and projects the laser beam onto the eyeball of the user, wherein the lens includes a first lens portion and a second lens portion located in this order from a side of the eyeball of the user, and a diffraction element located between the first lens portion and the second lens portion, and the laser beam enters the first lens portion from the side of the eyeball of the user, and is then reflected at an opposite surface of the second lens portion from the eyeball of the user to be projected onto the eyeball of the user.
 13. The image projection device according to claim 9, wherein the projection mirror includes a lens of glasses located in front of the eyeball of the user, the lens includes a first lens portion and a second lens portion located in this order from a side of the eyeball of the user, and a diffraction element located between the first lens portion and the second lens portion, and the scanned light composed of the laser beam enters the first lens portion from the side of the eyeball of the user, and is then reflected at an opposite surface of the second lens portion from the eyeball of the user to be projected onto the retina of the eyeball of the user. 